Drum-magazine for firearms.



K. KRNKA.

DRUM MAGAZINE FOR FIREARMS.

APPLIUATION FILED JULY 13, 1909.

Patnted Nov. 7, 1911.

2 SHEETSSHBET 1.

K. KRNKA. DRUM MAGAZINE FOB. FIREARMS.

APPLICATION FILED JULY 13, 1909.

Patented Nov. 7, 1911.

2 SHEBTSSHEET 2.

. rrnn STATES PATENT OFFICE.

KARL KRNKA, OF HIRTENBERG, AUSTRIA-HUNGARY.

DRUM-MAGAZINE FOR FIREARMS.

To all whom it may concern: Be it known that I, KARL KRNKA, engineer, a subject of the Emperor of Austria- Hungary, residing at Hirtenberg, in the Province of Lower Austria, Empire of Austria-Hungary, have invented certain new and useful Improvements in Drum-Magazines for Firearms; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

In drum magazines, as is evident from the nature of the case, the feeding of the cartridges into the receiver of the breech casing usually takes place somewhat from one side, so that the uppermost cartridge, ready for conveying into the receiver, does not lie immediately below the produced center line of the barrel, and must therefore be advanced in an oblique direction. In the case of ordinary magazine rifles this is no disadvantage, in automatic firearms however, where the operation of loading is effected very rapidly, this circumstance can give rise to trouble.

The delivery opening of the drum magazine into the receiver was hitherto arranged somewhat on one side for the purpose of allowing the magazine to be charged from packets by means of a cartridge frame inserted vertically into the weapon, as in the case of pressure directed against the longitudinal axis of the cartridge feeder the latter would not be able to rotate and a tangential motion from the side of the column of cartridges is therefore needed. The drum magazine under consideration however, eifects an exactly central supply of cartridges, although retaining the method of charging described above. At the same time it renders possible, which is most important, such a local disposal of the cartridges, that their bullet ends can rest directly behind the barrel without requiring an intermediate inclined surface between the barrel and the receiver. The locking grooves in the casing for the locking lugs, are not placed as is customary between the magazine and the barrel, but in the side walls of the breech, wherefore new conditions are given to this drum magazine to comply with modern requirements. For ex ample the inclined position of the uppermost cartridge necessary for its introduction into the receiver, is attained in a novel man- Specification of Letters Patent.

Application filed July 13, 1909.

Patented Nov. *7, 1911.

Serial No. 507,402.

ner for drum magazines. It is further proposed to arrange the whole magazine centrally in such a way as to remain unnoticeable from the exterior, without making this part of the stock any wider than is usual. By avoiding the cutting through of the stock, the latter can besides be left stronger, whereby warping is effectually prevented.

This magazine does not require a special method of taking to pieces, either by drawing or lifting out for example as it does not demand more frequent examination than for instance a trigger plate. The whole drum structure consists only of three parts made sufficiently strong, the drum, the cartridge feeder and the feeder spring.

Figure 1 shows a partial section and side elevation of the rifle in the condition previous to the charging of the magazine. Fig. 2 is a transverse section of the preceding view, along the line III of Fig. 1, with the magazine empty. Fig. 3 the same section when the magazine is full. Fig. 4 shows a section along the line III-IV of Fig. 1, looking tothe right, and illustrates the assembling of the magazine. Fig. 5 a transverse section through the breech casing, "with the magazine drum removed. Figs. 6 and 7 show the two faces of the drum. Figs. 8, 9 and 10 show a side view and the two end faces of the cartridge feeder. Fig. 11 shows the method of inclining the uppermost cartridge during its introduction into the barrel, and Fig. 12 is a. detail view showing the ejector.

, It may be clearly seen from Fig. 3 that the uppermost cartridge lies exactly in the center under the axis of the barrel and is located in its position by a peculiarly constructed rigid side rest 19, corresponding to the shape of the cartridge along its whole length. In Fig. 4: can also be seen the stepped part of this side rest 19, rendered necessary by the taper and the neck of the cartridge case. A vertical upward movement of the uppermost cartridge is prevented by the cartridge holder 7), shown in elevation in Fig. 1, and in section in Figs. 2 and 3. Fig. 3 shows that the cartridges are pushed forward into the slot 20 by a rotary movement of the cartridge feeder t in the drum .9, and rise until the uppermost cartridge engages the above mentioned side rest 19. This accurately formed rigid side rest 19, is obtained by boring a hole 9 (Fig. 5) beginning at the rear face of the receiver is, passing through the whole receiver underneath the middle bore and continuing in a tapered form corresponding to the shape of the cartridge. The necessary communication between this hole 9 and the drum 8 is established by means of the slot 20, stepped and tapered in a similar manner (Figs. 2, 3 and As the internal diameter of this slot 20 corresponds exactly to the shape of the cartridge, the uppermost cartridge will also attain the necessary inclined position for its introduction into the barrel although the bullet end is not guided at all; the cartridge must however be lifted sharply and rapidly as the bullet end lies close below the barrel. Fig. 11 shows, by means of a side View and two sections VVI and VIIVIII, the produced inclined posit-ion of the axis of the cartridge. The dotted double line l919 in the direction of the cartridge represents the rigid side rest described above, which is also shown in the sections V--VI and VIIVIII. As the slot is wider at the first mentioned section than at the second by means of the short advancing movement 21, the axis of the cartridge will be lifted through the height 23 at VIIVIII which, transferred to the side view at the same point, gives the bullet end a lift of height 23, whereby the cartridge can easily reach the receiver. At the commencement of the above advancing move ment therear end of the cartridge is kept low by means of the cartridge holder 1) (Fig. 1).

It will be seen from Figs. 1, 2 and 3 that the drum 8 as well as the cartridge feder is entirely inclosed in the stock. The drum 3 is made to slide drawer-wise in the receiver by means of the two flanges 24 (Figs. 1, 6 and 7) on the drum and the two grooves 25 (Figs. 1 and 5) in the receiver 76 which engage in each other. These flanges and grooves are stopped short in such a way that the drum can be pushed into its correct position on the receiver is from right to left but cannot be pushed through. In this position it is held fast by the feeder spring w, which tends to push the drum 8 through to the left. This spring to re ceives its required tension in sliding the drum into position as will be hereinafter seen.

The cartridge feeder t (Fig. 8) has a long projecting rib 26 in addition to several short ribs for feeding the cartridges. The pivots 27 and 28 turned on the cartridge feeder, serving as its axis rest in the slotted bearings 29 and 30 on the drum .9 (Figs. 6 and 7 and are retained therein by the receiver as may be seen from Fig. 1, so that they can rotate only. In milling the bearing surface for the feeder spring w the pivot 28 is formed at the same time, or else such a pivot 28 can be permanently attached to the bearing for the spring, so that the cartridge feeder consists of a single rigid part. The feeder spring w has its two ends bent, one of which is inserted in the small drilled hole 31 in the feeder, and the other in the slot 32 of the drum (Figs. 1, 7 and 10). These two ends of the spring 10, lie radially opposite each other in its free untwisted position, in Fig. 1 this in not shown to be the case, as the spring there possesses its initial twist of 180. The feeder spring w, is first placed on its bearing in the cartridge feeder in such a way that one end of the spring rests in the drilled hole 31. The cartridge feeder together with its spring is then inserted into the drum with the long rib 26 pointing downward, whereby the bent front end of the spring w, falls by itself into the small slot 32. By means of the long rib 26, the cartridge feeder which is already placed in its bearings is then turned outward through 180 in the direction of coiling the spring (2'. e. from below to the right). The drum is then slipped into the receiver 70 (as shown in Fig. 4) the long rib being tilted still farther in the direction of coiling, this being repeated in the case of the following short rib 33, in order that the latter can pass the first impeding wall of the receiver. As soon as this has been carried out and in consequence of the twisting of the spring, the drum will slide by itself into its final position (Fig. 2) since the spring will tend to untwist further. In order to take them apart, the drum need simply be pushed out to the right while overcoming the force of the spring.

The shoulders 34 and 35 (Figs. 1 and 2 serve to guide the cartridges from the U shaped drum 8, to the slot 20 whose lefthand lateral surface is tangential to the internal periphery of the drum. The latter is in the form of a semicircle with the exception of the above shoulders 34 and35.

It is of particular value in the case of automatic firearms that the weapon after discharging the last cartridge, should automatically set itself ready for charging, for which purpose the feeder ordinarily moves into the path of the breech bolt. In the case under consideration, the long rib 26 (Fig. 1) can not perform this duty, because neither the path of the head at of the breech closing piece, nor that of the breech bolt 6 or its locking lugs (Figs. 1 and 5) can touch the magazine chamber since the special connecting passage 20 is located between the drum and the receiver. The long rib 26 can never reach up high enough, as its height is determined by the internal radius of the drum. For this reason a rod it (Fig. 12) is used in the case of this drum magazine, and can be seen in Figs. 1 and 5. This rod also serves as a cartridge ejector for the breech bolt 6, but in the case under notice it is constructed in such a way, as shown by Fig. 1, that it strikes the long rib 26 when the magazine is empty. It is dragged to and fro by the breech bolt which engages with the toot-h 10 on the said rod (Fig. 12) and is shaped to correspond to the bored hole 9 (Fig. 5) in order that it cannot drop into the slot 20 (Figs. 2, 3 and 11). For drum magazines this rod it therefore represents a new means for a known end, serving not only the ordinary function of an ejector but also as a stop for the breech bolt.

I claim as my invention 1. In magazine firearms, the combination with a receiver provided with an inclined feed slot cut away on one face to provide an inclined rest for the entire length of the cartridge, of a drum magazine connected to said receiver, a rotary cartridge feeder mounted in said drum, and automatic means for rotating said cartridge feeder, whereby the cartridges are fed seriaz im to feed said. slot, substantially as described.

2. In magazine firearms, the combination with a receiver provided with an inclined feed slot cut away on one face to provide an inclined rest for the entire length of the cartridge, of a drum magazine transversely slidably connected to said receiver, a rotary cartridge feeder mounted in said drum, and a coil spring connected at one end to said drum magazine and at the other end to said rotary cartridge feeder, whereby the cartridges are fed scrictim to said feed slot, substantially as described.

3. In magazine firearms, the combination with a receiver provided with an inclined feed slot cut away on one face to provide an inclined rest for the entire length of the cartridges, of a drum magazine slidably connected to said receiver by a movement at a right angle thereto, a rotary cartridge feeder mounted in said drum and provided with a plurality of teeth and an elongated rib projecting radially from one of said teeth, and automatic means for rotating said cartridge feeder, whereby the cartridges are fed sematz'm to said feed slot, substantially as described.

4. In magazine firearms, the combination with a receiver provided with an inclined feed slot cut away on one face to provide an inclined rest for the entire length of the cartridges, of a drum magazine connected to said receiver, a rotary cartridge feeder mounted in said drum and provided with a plurality of teeth and an elongated rib proj ecting radially from one of said teeth, automatic means for rotating said cartridge feeder, whereby the cartridges are fed scri- (m'm to said feed slot, and an ejector provided with a lug adapted to engage the breech bolt, and the front end of said ejector engaging said elongated rib when the latter is rotated to the raised position, thereby locking the breech block against forward motion when the magazine is empty, substantially as described.

5. In magazine firearms, the combination with a receiver provided with an inclined feed slot cut away on one face to provide an inclined rest for the entire length of the cartridge, of a drum magazine slidably connected to said receiver by a transverse movement, a rotary cartridge feeder mounted in said drum and provided with a plurality of teeth and an elongated rib projecting radially from one of said teeth, a coil spring connected at one end to said drum magazine and at the other end to said rotary cartridge feeder, whereby the cartridges are fed sem'atim to said feed slot, and an ejector provided with a lug adapted to engage the breech bolt, and the front end of said ejector engaging said elongated rib when the latter is rotated to the raised position, thereby locking the breech block against forward motion when the magazine is empty, sub stantially as described.

6. In magazine firearms, the combination with a receiver, of a drum magazine slidably connected to said receiver by a movement at a right angle thereto, a rotary cartridge feeder mounted in said drum and recessed to receive and protect the feed spring, and a coil feed spring mounted in said recess and connected at one end to said drum magazine and at the other end to said rotary cartridge feeder, substantially as described.

7. In magazine firearms, the combination with a receiver provided with an inclined fe'ed slot cut away on one face to provide an inclined rest for the entire length of the cartridge, of a drum magazine slidably connected to said receiver by a movement at a right angle thereto, a rotary cartridge feeder mounted in said drum and recessed to receive and protect the feed spring, and a coil feed spring mounted in said recess and connected at one end to said drum magazine and at the other end to said rotary cartridge feeder, whereby the cartridges are fed sem'ctim to said feed slot, and the magazine is automatically held in place, substantially as described.

8. In magazine firearms, the combination with a receiver, of a drum magazine slidably connected to said receiver by a transverse movement, a rotary cartridge feeder mounted in said drum and recessed to receive and protect the feed spring, and a coil feed spring mounted in said recess and connected at one end to said drum magazine and at the other end to said rotary cartridge feeder, whereby the cartridges are fed serz'atz'm to said feed slot, and the magazine is automatically held in place, substantially as described.

9. In magazine firearms, the combination a lateral movement, the drum being provided With circular shoulders 34 and 35 for guiding the cartridge laterally, a rotary cartridge feeder mounted in said drum, and

a coil spring connected at one end to said- Gopies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

drum magazine and at the other end to said rotary cartridge feeder, substantially as described.

In testimony whereof, I aflix my signature in presence of tWo Witnesses.

KARL KRNKA.

Witnesses:

JULIUS J. FEIFFER, ROBERT W. HEINGARTNER.

Washington, D. C. 4 

